Field of the Disclosure
The invention relates in general to bearings and tolerance rings and, in particular, to an improved system, method and apparatus for a maintenance-free bearing assembly with tolerance compensation properties against wear and misalignment.
Description of the Related Art
Bearings and tolerance rings constrain movement between parts that move relative to each other, such as rotating shafts in housing bores. An example of such a structure is an annular band located in the gap between the outer surface of a shaft and the inner surface of a bore. This tolerance ring limits radial or axial motion of the shaft within the bore while still permitting relative movement.
In conventional designs, a close fit is sought between the inner and outer components. In addition, either forces for providing maximal frictional engagement or minimal variation in sliding forces are sought. A close fit between the components is desirable because it reduces relative vibration between the parts. Tolerance rings are able to compensate for tolerances or misalignments, create torque and can improve other properties, such as noise, vibration and harshness properties. Such properties and torque are mainly influenced by the material properties of common tolerance rings, which are usually formed only from stainless or carbon steel. These requirements between the inner and outer components require strong and substantial contact, which increases frictional forces.
For example, a conventional bushing 31 (FIG. 3A) comprising a backing layer 33 and plastic compound 35 is located between a pin 37 and housing 39. When a significant force F (exaggerated in FIG. 3B) is applied to the pin 37, the bushing 31 is deformed and excessively worn, and undesirable contact or uneven friction occurs between the pin 37 and backing layer 33. Although these solutions are workable for some applications, improvements in bearings and tolerance rings continue to be of interest.